This is a Knot Assist electric knotter, a line tying tool for connecting PE lines and shock leaders. It's the perfect item for making rigs and for connecting PE lines and shock leaders in lure fishing. I bought it new and have tried tying knots with it a few times at home, but it's in like-new condition as I haven't taken it out fishing. [How to Use] An English instruction manual is included, but it might be easier to understand if you search for "line tying machine" or "line knotter" on YouTube and watch a video. [Contents] Line tying machine body x 1 Spool clip x 1 English instruction manual x 1 [Body Size] Length: Approximately 11cm Width: Approximately 6cm Thickness: Approximately 2.3cm (at the thickest part) [Compatible Lines] PE Line: 0.6 to 3 Leader: 1.5 to 12